It has been too long since this machine last replicated with the named source machine. The time between replications with ...

It has been too long since this machine last replicated with the named source machine.  The time between replications with this source has exceeded the tombstone lifetime.  Replication has been stopped with this source.  
The reason that replication is not allowed to continue is that the two machine's views  of deleted objects may now be different. The source machine may still have copies of objects  that have been deleted (and garbage collected) on this machine. If they were allowed to  replicate, the source machine might return objects which have already been deleted.  
Time of last successful replication:
%1  
Invocation ID of source:  
%2  
Name of source:  
%3  
Tombstone lifetime (days):  
%4  
  
The replication operation has failed.
  
User Action:
  
Determine which of the two machines was disconnected from the forest and is now out of date.  You have three options:  
  
1. Demote or reinstall the machine(s) that were disconnected.  
2. Use the "repadmin /removelingeringobjects" tool to remove inconsistent deleted objects and  then resume replication.  
3. Resume replication. Inconsistent deleted objects may be introduced. You can continue replication by using the following registry key.  Once the systems replicate once, it is recommended that you remove the key to reinstate the protection.  
  Registry Key:
HKLM\System\CurrentControlSet\Services
TDS\Parameters\%5